What determines the law requiring the use of car seats and/or safety belts for children?

The law requiring the use of car seats and/or safety belts for children is primarily determined by both weight and age. This is because these factors help establish the appropriate form of restraint needed to ensure a child’s safety during travel.

Children's bodies differ significantly in size and strength as they grow, so regulations take into account their development. For example, younger children and those who weigh less may not be adequately protected by a standard seat belt alone and require a car seat designed for their size and weight to provide the necessary support in the event of a crash. As children age and reach certain weight thresholds, they may transition from a car seat to a booster seat, and eventually, to using just a seat belt, which reflects their ability to safely use adult restraints.

In contrast, height alone does not fully account for safety needs, as a shorter but heavier child may require different restraints than a lighter child of the same height. Age-only regulations can overlook individual growth patterns and safety needs. The type of vehicle is generally not a determining factor in these laws, as safety regulations are set to ensure children are protected regardless of the vehicle being used.